Questions on the Supra vs. the Z4 M40i specifically the B58 engine

"KingT- 60% of the time, it works every time" (kngt)
05/13/2019 at 15:55 • Filed to: supra, toyota supra, z4, BMW z4, z4upra

Z4UPRA

Do we have any official explanation from Toyota or any knowledgeable sources on why they detuned the engine for the Supra vs Z4?

Here are the specs for reference:

Z4 has 382 hp between 5,000 and 6,500 rpm, plus 369 lb-ft. of peak torque from 1,600 to 4,500 rpm. 0 to 60-3.9 seconds. It bests the Supra’s 4.1-second time, which makes sense since it has 47 extra horsepower and only weighs 46 extra pounds.

I know 3.9 vs 4.1 is not something anyone can feel in real world driving but under <4.0 s official does give you bragging rights. Although I do recognize that the Supra is a better deal per $ when you can get only the 4 cylinder Z4 for $50K.

Was it cost? reliability concerns? fuel efficiency? holding back for a more powerful version in the future (read:more profit)?

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DISCUSSION (21)

lone_liberal > KingT- 60% of the time, it works every time
05/13/2019 at 16:02

I don’t know, but I would bet it was an agreement between BMW and Toyota to differentiate the two in the market. BMW gets the higher power and cost, Toyota gets the lower. That way they don’t compete directly.

Spanfeller is a twat > KingT- 60% of the time, it works every time
05/13/2019 at 16:03

Some say reliability... I think maybe something with emissions?

In the end, a basic flash of the ECU would give you a 380 or 400 hp Supra. The transmission can certainly hold it too.

davesaddiction @ opposite-lock.com > KingT- 60% of the time, it works every time
05/13/2019 at 16:04

OEM horsepower ratings these days, especially for turbocharged cars, don’t seem to be terribly accurate. BMW seems to lowball their power numbers. Who knows what Toyota decided to do with their OEM numbers?

OEM 0-60 numbers are also variable. Some makers are conservative (with reviewers being able to beat them consistently ), and some are right on. This was the initial rollout - we’ve had no instrumented tests with the Supra yet.

The only thing I know is, when the fuel gauge in a German car says the tank is empty, it’s really empty, and when a fuel gauge on a Japanese car says it’s empty, you’ve still got 2 gallons...

KingT- 60% of the time, it works every time > Spanfeller is a twat
05/13/2019 at 16:06

Possibly emissions. I saw this on Wikipedia notice how EU emissions compliant G20 M340is use the 335HP version?

Kinja'd!!!

KingT- 60% of the time, it works every time > davesaddiction @ opposite-lock.com
05/13/2019 at 16:09

BMW has always underrated their engines as many dyno tests have proven (Even with the variations between dyno results) so that 382/335 might actually even be at the wheels, you never know.

As for 0-60 I am waiting for the inevitable Z4 vs Supra instrumented test from C&D, Motortrend. But as it stands to day the Z4 is faster by a hair.

random001 > KingT- 60% of the time, it works every time
05/13/2019 at 16:10

I think it’s only detuned on paper....

Vicente Esteve > KingT- 60% of the time, it works every time
05/13/2019 at 16:13

If what I have read is true, then the tuning that Toyota did for the engine may loose on HP due to something else (Durability?)

Either way, BMW rates its horsepower pretty damn low. Sort of a worse case scenario horsepower so I can only really trust dynos

davesaddiction @ opposite-lock.com > KingT- 60% of the time, it works every time
05/13/2019 at 16:17

If the 0-60 difference is real, it could just be down to transmission tuning. The Z4 is set up for more GT driving, while the Supra will be at home on the track.

His Stigness > KingT- 60% of the time, it works every time
05/13/2019 at 16:18

As many have pondered it may be because of durability, but I’ll believe that if we find out what the warranty terms are between the company. Did Toyota have to agree to honor all warranty costs for the Supra? Was it just the power train ?

But of course we’ll never know since Toyota just continues to spout utter bullshit about the Supra and go to great lengths to try and convince people they played a huge part in the development. But since nothing in that car carries a Toyota logo, I don’t buy any of it. I wouldn’t even be surprised if Toyota engineers were even involved in testing the cars, and instead just gave BMW a brief on how they wanted the car to turn out.

Nick Has an Exocet > KingT- 60% of the time, it works every time
05/13/2019 at 16:22

I’m wondering how many differences there really are. On the 0-60, I’m wondering if the BMW has a longer 2nd gear or taller rear end. That would explain that if the engines are the same but rated differently due to manufacturers.

Shift24 > KingT- 60% of the time, it works every time
05/13/2019 at 16:43

Some Internals , cylinder head, and turbos are different. And knowing bmw I bet toyota made those changes for reliability. BMW likes to run their motors hot so Toyota may have changed cooling.

Also I hope Toyota supplied their own rubber gaskets because BMW still can make one that goes past 100k

https://www.roadandtrack.com/new-cars/future-cars/a26064082/toyota-supra-bmw-z4-engines/

Spanfeller is a twat > KingT- 60% of the time, it works every time
05/13/2019 at 16:51

Makes sense, the Z4 M40i is sold as a 340hp car in Spain.

WilliamsSW > KingT- 60% of the time, it works every time
05/13/2019 at 16:51

I recall reading somewhere that Toyota agreed with BMW on the power figure, which was ( at the time) what BMW was claiming for the engine. See power ratings for the B58 in last year’s 3 series.

Then BMW tuned it up to 382 and kinda sorta didn’t tell Toyota about it.

So Toyota seemed surprised that the Z4 has 382 HP actually.

Think I read that in an interview with Toyota’s engineering head on the project - probably on the FP?

404 - User No Longer Available > KingT- 60% of the time, it works every time
05/13/2019 at 17:06

It’s not fuel economy nor octane, that’s for sure.

https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=41309&id=41374

Textured Soy Protein > KingT- 60% of the time, it works every time
05/13/2019 at 17:08

The 382 hp tune on the Z4 (and M340i, and probably other future M40i models) is unique to the US and certain other markets where emissions laws haven’t been tightened up quite as much as Europe. But in those markets the Z4 makes that same 335-340ish hp as the Supra.

My guess is Toyota didn’t want to develop and certify two different states of engine tune in different markets, all for just the Supra, vs BMW will end up using that 382 hp tune in lots of models. Hell, the M340i in the US might sell more than the Supra worldwide.

Manwich - now Keto-Friendly > KingT- 60% of the time, it works every time
05/13/2019 at 17:16

My guess is that it’s done for reliability/durability reasons.

Though neither Toyota nor BMW would ever admit it.

KingT- 60% of the time, it works every time > Textured Soy Protein
05/13/2019 at 17:20

makes sense

KingT- 60% of the time, it works every time > Shift24
05/13/2019 at 18:11

That link was helpful thanks!

burtmacklin > KingT- 60% of the time, it works every time
05/14/2019 at 10:42

BMW changed motors without telling Toyota. They didn't find out 1 year before, which doesn't give enough time to change theirs. MY21 Supra will have the newer motor with the same power figures.

davesaddiction @ opposite-lock.com > KingT- 60% of the time, it works every time
05/14/2019 at 18:55

3.8 per C&D

Tapas > KingT- 60% of the time, it works every time
05/16/2019 at 09:55

Supra with Z4 front end? NotBad.jpg.

The Z4 vents are still over styled if you ask me...

I hope there are plenty of aftermarket sharper and less fussy front end options for both cars. I’d even love it if Supras did a Targa version!

Supra is definitely the car to get out of the two. At least until the Z4M comes out.